19 Diagnostics library [diagnostics]

19.3 Assertions [assertions]

19.3.3 The assert macro [assertions.assert]

An expression assert(E) is a constant subexpression, if

(1.1)
NDEBUG is defined at the point where assert is last defined or redefined, or
(1.2)
E contextually converted to bool is a constant subexpression that evaluates to the value true.